The clinical study of neuro-attenuated replication competent HSV-1 mutants deleted for gamma-34.5 and ICP6 and amplicon vectors has been limited by the inability to consistently produce vector stocks in adequate quantity and quality. The goal of Core B will be to provide program investigators with MGH2 (gamma-34.5/ICP6 mutant) and amplicon viral stocks that are both high in titer and highly purified while Deing consistently produced according to vector specific protocols. Vector stocks produced in this manner will be characterized across all major quality control areas that make up lot release criteria of DNA viruses for clinical use. This approach will result in generation of pre-clinical data that will not be hampered by issues of bio-equivalency between vector stocks that are used for pre-clinical studies and those that may be used later in a clinical setting. The use of highly purified and characterized vector stocks will also allow program investigators to more completely understand the potential efficacy and mechanism of activity of vector delivery in the pre-clinical setting without the worry of spurious results that may result from the use of nonuniform vector stocks or vector stocks that are contaminated with wild type virus or high levels of defective particles, contaminating proteins, or host cell DNA.